Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 16: Poster: Colloids and Complex Liquids

CPP 16.25: Poster

Dienstag, 27. März 2012, 18:15–20:45, Poster A

Predicting the Soret coefficient in binary mixtures via an additiv model of the heats of transport — •Florian Schock, Steffen Hartmann, and Werner Köhler — Physikalisches Institut, Universität Bayreuth

Diffusion in a binary mixture not only originates from a concentration but also from a temperature gradient. The so-called Soret coefficient, which is the ratio of thermal diffusion coefficient and mutual mass diffusion coefficient, can be expressed by non-equilibrium quantities - the heats of transport -, and a thermodynamic factor that can be obtained from equilibrium properties. We have measured the Soret coefficient of a large number of binary mixtures of organic solvents at least at three different concentrations. The thermodynamic factors have been determined from the group contribution method Modified UNIFAC (Dortmund). We have found an additive model for the heats of transport of equimolar mixtures. This allows to predict the Soret coefficients of all possible symmetric binary mixtures from the measurement of a single system. The procedure is exemplified for a series of alkanes in comparison with existing data for a large number of solvents.